Wednesday, 6 March 2019

PiWars 2019 - An adventure in spaaaaaace!

PiWars 2019, the Raspberry Pi robotics challenge competition, is returning at the end of this month and, after a years break, I'll be returning as a competitor. Alas I'm a tad behind on my blogging this time around, I did start writing this entry in 2018 but never quite finished it!

Too small!

PiWars 2019 is based around a space theme, to celebrate 50 years of space exploration, and as such I was looking at robot designs that fit into this theme. My initial thoughts were to do another 3D printed robot chassis, this time based around NASA's Lunar Roving Vehicle. But after reviewing images of it, and reading through the manual, I came to the conclusion that the LRV's design is too minimal to successfully incorporate the Raspberry Pi, motor driver and sensors. At least at the scale needed to conform to the competition's size restrictions.

Too large!

My first forays into Raspberry Pi based robots was around modifying toys, and I have built up a collection over the years that I've been planning on converting. Amongst these were a couple that met the space theme criteria.
One was far too long and the other I initially thought was too wide, but, after double checking the rules, I realised that the accepted width is actually slightly larger than an A4 sheet and my choice was made!

Just right!

So for PiWars 2019 I will be converting a Wall-E toy, specifically the 10" U-Command Wall-E, removing the existing electronics and replacing them with a Raspberry Pi, plus any sensors required to complete the courses. A quick search on the internet finds numerous projects that involve modifying this Wall-E toy, which can provide much in the way in inspiration, as well as knowledge on how to open up and dismantle the toy without irreversible damaging it.

The initial list of requirements I came up with are as follows

Built around a Raspberry Pi 3A+.

This provides the built-in WiFi/Bluetooth and CPU power of the 3B, but in a smaller package that will help maximise the available space inside Wall-E.

Minimise external changes to the chassis

Quite a few of the existing Wall-E conversions found online make large, visible changes to the body. Such as cutting away the motor housings to install servos. Ideally I'd like an end result where you have to look closely to spot the modifications

Install a laser ToF sensor

Several challenges require detecting how far away from a wall a robot is. A laser sensor will provide this ability in the smallest package.

Install a Raspberry Pi camera

A number of the autonomous challenges require some level of visual processing. So the installation of a camera is a must. Ideally this will be in Wall-E's head, but failing that on the front of the body.

Install an LCD/OLED to replace the battery usage

Having a UI on the robot is often useful for launching challenge specific scripts and check on his status, without having to carry around a laptop. To keep this in theme I'd want to replace the battery level screen for this.

The first step is, of course, opening up Wall-E and working out how to fit everything inside. Which I will cover in my next update!.